The MISSING_PUBKEY error is not clear enough

[ShookLyngs]

The MISSING_PUBKEY error is usually triggered when the generating BTC transaction contains P2TR inputs, but no relevant pubkey was provided to the TxBuilder in the first place. Without the information of pubkey, the transaction cannot be built.

The current error message is not very clear and could end up confusing users:

Missing a pubkey that pairs with the address: {address}